Final answer:
The requirement to act as pilot in command of an airplane with passengers aboard is at least three takeoffs and three landings in the same category, class, and type within the preceding 90 days.
Step-by-step explanation:
To act as pilot in command of an airplane with passengers aboard, the Federal Aviation Regulations require at least three takeoffs and three landings in an airplane of the same category, class, and type (if applicable) within the preceding 90 days. These landings, if conducted in a tailwheel airplane, must be to a full stop, which emphasizes the importance of these skills in case of differing aircraft characteristics. This rule exists to ensure that the pilot has recent flight experience and is proficient in the aircraft they intend to fly.